Manufacture of ferrochromium.



PATENTED OCT. 29. 1907.

H. W. 0., ANNABLE. MANUFACTURE OF FERROGHROMIUM.

AIWLIOATION FILED OUT. 31. 1908.

I INVENTOK I Wk m,

ATTORNEYS I v UN D 'STATES' PATENT, OFFICE.

FERROALLQYS SYNDICATE LIMITED, OF LONDON, ENGLAND.

If, for example, the initial material taken be chrome iron ore, (chromite), containing not less than fifty per cent. of chromium sesquioxid, I grind it finely and then I wash and concentrate it in any suitable concentrating machine in order to remove, as far as pos- Bible, the mechanically mixed impurities, such as silicious and earthy ingredients. With the ore Lhus treated I intimately mix carbonaceous material, (preferable ground anthracite), slightly in excess of the quantity theoretically required to reduce the chromic andiron oxids to the respective metals, and sufiicient fiuxing matter, (such as cryolite, ,borax, fluorspai,

chlorid of calcium, or glass), to form a flux with the magnesia, alumina, and silica, in the ore, which flux will be fusible at a bright red heat. Alkaline fluxes should be avoided as they tend to absorb, chromium,

and-this mixture I heat in a refractory receptacle.

The crude fused form-chromium thus formed after cooling is removed from the receptacle and broken up.

Ill-order to prepare form-chromium free, or practi- Cally free, from carbon from the crude ferro-chromium thus or otherwise prepared, 1 mix the crude ferr'o-chrom iur'n with pure oxid of iron, suflicient in quantity to make the proportion of the chromium in the mixture about equal to that of the total iron, calculated-as metal. The quantity of carbon in this mixture must be in excess of the arbon necessary to reduce to metallic iron the whole of the oxid of iron mixed with the crude form-chromium. The mixture thus prepared is then introduced into a refractory receptacle oxid of iron being contained in a space, or receptacle, beneath the space or receptacle containing the mixture, so that the fem-chromium, smolted with the mixture, will pass through the said oxid of iron. The mixture may for this purpose, be supported on a perforated false bot tom leaving a space beneath for the oxid of iron, or the receptacle containing the mixture .may be open at bottom and be mounted upon another refractory receptacle containing the oxid of iron. The receptacle, or receptacles, is, or are, then closed and heated to say a white heat .(about from 1300 to l400 centigrade)2 Owing to the higher temperature and to the I additional iron formed by the reduction of the oxid of iron Specification of we Patent. Application filsd October 31. 1906- Ssriallio. 341.48 1- nxuumcrrmn-*oi i n'aaocnnomon.

Patented Oct. 29, 1907.

mixed with. the charge, the crude fem-chromium fuses. Meanwhile,'the oxid of iron in the space at the bottom of the receptacle (or in the lower receptacle where that is used), attains the same, or a higher, temperature and the fused ferro-chromium when the necessary temperature is obtained, percolates through the said oxid of iron and is obtained as a fused mass. If the ferro-chromium contain carbon when itcomes into contact with the hot oxid of iron beneath, this carbon reduces aproportionate amount of the oxid of ironic iron, which slightly raises the percentage of iron in the ferr0-chromium. I

.HENRY ILLIAM oourn ANNABLE, or sATrERsiaA, LONDON, ENoL'ANb, ASSIGNOR TO THE If chromite be used as the initial material, the 'mcess may be carried out inone operation by mixing the tacle of a double arrangement of receptacles, the lower one containing oxid of iron as hereinbefore described. I

The form-chromium must be in contact with the oxid of iron for a sufficient-time to 'reduce all, or practically all, of the carbon present in the fem-chromium, but

not long enough for iron from the oxid of iron to replace chromium inthe fend-chromium to any material extent. This may be doneby using the oxid of iron in a-layer of such depth that examination of the product ing the mixture to fusing point in the upper recepwhich has passed through it shows that Z111, or praetically all, of the carbon has beenremoved, andthat all, or practically all, of the original chromium in the ore is presentin the refined product.

Outlets for the escape of gas will be provided. The ferro-chromium-can be allowed to collect and solidify in the lower space, or receptacle, or it can be run ,off therefrom through a tap-hole. l

The accompanying drawing represents apparatus adapted for the purposes of this invention.

A is an upper furnace containing a crucible/B, and C is a lower furnace containing a crucibleD. These furnaces are each heated by a burner E provided with wire gauze at e, and with inlets for coal .spectively at f and g.

The upper crucible B contains the ferro-chromium with carbon in admixture with oxid of iron, and .has an opening I) through which the molten ferro-chromium descends in contact with oxi'd of iron supported on the perforated support din the crucible D, the purigas and air refled ferro-chromium running out by the tap hole (I c are outlets for gas. I claim as my invention 1. The process of manufacturing terro-chromlum substnntially free from carbon which consists ln.smelting crude terrocliromlum in the presence of carbon and oxld of iron and out of contact with the products of combustion and then passing the molten fcrro-chr0mlum through a bed of oxid. of iron to reduce the carbon present, substantially as described.

2 The process of manufacturing form-chromium suband over a bed of oxid of irnn and then dropping thr smntiully tree from carbon which consists in snmlting molten fcrro-chrominm in a continuous stream through tlncrude ferrn-chr0mlum in the prcsvnce of carbon and oxid said bed of oxid of iron to rcducu thc carbon nrcsrnt, sub- 01' iron and ut of contact with the products of combustion stantially as tlcscribctl.

5 and then passing the molten tcrro-cliromium in n cnntin'lr In tvstinmuy \vln-rvof I have signed this Sllttllltfilljt) in K ous Sllllllll through a bed of oxid of iron to reduce the car 4 the proscncc of two subscribing \vitnns.\

' hon prnsvnt, substantially as LIOSCl'ilKll.

HENRY \VILLIAM tJOlll'lC ANN/UNA). i

The process of manufacturing fcrro-clironiium sub stuutinlly free from can-bun which consists in smelting 10 crmlr l'vrru-clmnniunt in tin; presence 01' cnrbon and (mid nf iron and out. of contact with the products of combustion Witnesses WILLIAM Gnruin Rmrvmms, Glmmn'r Fmc'rcnnn 'lrsux. 

